The original links to the conference talks are at the London City Mission site. You can stream the messages there rather than downloading if you like, but that's like going to P.F. Chang's once without ever returning. It's just stupid. Enjoy!
By the way, the beginning of the first talk Keller talks about what "missional" is, what a "missional church" looks like. The whole talk is in that direction, but the start was particularly interesting.